"Assange to be arrested under all circumstances," the hand-written note says.

The briefing paper, captured by an eagle-eyed photographer as an official carried it in his hand, lays out the major difficulty the WikiLeaks founder faces, even though he's received diplomatic asylum. He's safe as long as he remains in the embassy. The minute he steps outside, he faces immediate arrest — and speedy extradition to Sweden — over sex crimes allegations leveled against him there.

Scotland Yard acknowledged the hand-written note was from a briefing and stressed that the force's objective is to arrest Assange for breach of bail.

"Under no circumstances would any arrest be made which was in breach of diplomatic immunity," Scotland Yard said.

The embassy standoff has the potential to drag on for weeks, months, or even years, and it's one that has pitted the United Kingdom — which has warned it could revoke the embassy's status if diplomats continue to shelter the Australian computer expert — against the small Andean nation of Ecuador and many of its left-leaning Latin American allies.

The world's media have followed every move in the increasing convoluted WikiLeaks saga — which has elements of journalistic intrigue, conspiracy theory, legal wrangling, and international diplomacy.

The latter got the most play Friday, with the Ecuadoreans saying that several South American diplomats had visited the embassy in solidarity with Ecuador's stand against Britain's warning.

Argentina, which fought a brief war with Britain in 1982 over the Falkland Islands — also known as the Malvinas — took the opportunity to scold London for the move, which it described as a "violation of international law."

"This action shows the arrogance of British diplomacy," the Argentinian Embassy said in a statement. "It doesn*t come as a surprise for Argentinians, as it is similar to the British statements on the Malvinas Question, in which the U.K. has also disregarded international law."

Britain's Foreign Office said earlier that it had delivered a letter to Ecuador's Embassy — but declined to say what was in it. Neither side shows any sign of budging any time soon.